Air assisted enclosed combustion device

ABSTRACT

Air Assisted Enclosed Combustion Devices (AAECD) and methods are disclosed that provide maximum destruction efficiency of VOC&#39;s and methane greenhouse gases produced by oil production, site processing, storage, and transmission operations and produces no visible emission (smoke, soot, particulates) in the process. An exemplary AAECD may include a housing with an outer housing and a burner housing separated by an air gap. The AAECD is provided with a burner assembly, a blower assembly, and a suite of sensors in communication with an electronic control module having logic configured to receive input signals from the sensors, calculate an actual fuel-air ratio using the received input signals, compare the actual fuel-air ratio to a fuel-air ratio setpoint, and adjust a position of a throttle valve to control a rate and volume of air from a blower motor to the burner if the actual fuel-air ratio and the fuel-air ratio setpoint are different.

INCORPORATION BY REFERENCE

The present application claims priority to a provisional patent application identified by U.S. Ser. No. 63/008,240, filed Apr. 10, 2020, titled “Air Assisted Enclosed Combustion Device,” the entire contents of which are hereby incorporated herein by reference.

BACKGROUND

The environmental protection agency (EPA) identifies and regulates emissions that may be harmful to humans or the environment in the United States. Volatile organic compounds (VOCs) and methane are included in the list of regulated emissions established by EPA. Oil and gas production, processing, storage, and transmission produce VOCs and methane that escape into the atmosphere. Flares and enclosed combustion devices (ECDs) are used to control the emissions from these processes. The EPA has established emission standards with which ECDs must comply.

As of Aug. 2, 2016, the effective date of the final standards rule, ECDs must reduce the mass content of VOC emissions by 95% or greater and produce no visible smoke. To date, there are approximately 47 ECDs from 24 companies that have either successfully demonstrated compliance with the standard or have their test results under review by EPA for compliance.

In-use observations support that many of these 47 ECDs do not provide expected performance under real-world conditions. The most common observation is visible emissions (smoke) during low flow and transients fueling conditions. Smoke is produced during extreme rich combustion when there is a lack of oxidizer (air) to support complete combustion. Operators that use ECDs that emit smoke are subject to monetary fines each time visible smoke is emitted. These operators are requesting ECDs that not only meet the EPA standard, but do not smoke under any reasonable operating conditions.

No ECDs meet or exceed EPA requirements under all normal ambient conditions without manual adjustment by an operator. Thus, there is a need for an ECD that will run autonomously and meet EPA standards under all reasonable and normal operating conditions. Such an apparatus and the method of operation thereof are the subject of this disclosure.

SUMMARY OF INVENTIVE CONCEPTS

An ECD is described that provides high destruction efficiency of VOCs and methane greenhouse gases while emitting no visible emissions (smoke/soot) over full range of its operation. This level of operation is accomplished autonomously over a wide range of ambient conditions with no human intervention by controlling a fuel-air ratio in burner(s) in the ECD using a variable-speed blower controlled by an electronic control module (ECM) that receives input from a plurality of sensors and calculates a desired air flow rate needed for complete combustion of a feed fuel. The electronic control module adjusts a speed of the variable-speed blower to obtain the desired air flow rate to the burners. Feedback sensor(s) in an exhaust are used to further optimize the air flow rate to adjust the fuel-air ratio to account for changing conditions such as fuel composition, local weather (i.e., barometric pressure and air temperature), production part-to-part variability of a fuel-air nozzle(s), variable-speed blower, and VFD, and repeatability, accuracy, and temperature drift of the sensors, for instance.

Consistent with an aspect of the present disclosure, an exemplary enclosed combustion device may comprise: a housing comprising an outer housing and a burner housing, the burner housing situated inside the outer housing and separated from the outer housing by an air gap; a temperature sensor and an exhaust gas oxygen sensor mounted to the burner housing; a burner assembly mounted inside the burner housing for burning a fuel, the burner assembly having at least one burner connected to an air manifold and a fuel manifold, the fuel manifold having a fuel supply pressure sensor and connectable to a source of the fuel; a blower assembly connected to the air manifold, the blower assembly having a blower motor, an air plenum, and a throttle valve controller operably connected to a throttle valve situated inside the air plenum; and an electronic control module having a processor and a non-transitory computer readable memory storing logic, the electronic control module in communication with the throttle valve controller, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor; wherein the logic of the electronic control module is configured to receive input signals from the throttle valve controller, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor and cause the processor to calculate an actual fuel-air ratio using the received input signals, the logic further configured to cause the processor to compare the actual fuel-air ratio to a fuel-air ratio setpoint and the cause the processor to signal the throttle valve controller to cause the throttle valve controller to move the throttle valve to a desired position to control a rate and volume of air from the blower motor to the at least one burner if the actual fuel-air ratio and the fuel-air ratio setpoint are different. In some implementations, the electronic control module is configured to operate the enclosed combustion device in a closed-loop by calculating the actual fuel-air ratio and comparing the actual fuel-air ratio to a fuel-air ratio setpoint at predetermined intervals. In some implementations, the closed-loop is further defined as a first-closed loop that determines a position of the throttle valve at a first predetermined interval and a second closed-loop that determines the actual fuel-air ratio and compares the actual fuel-air ratio to the fuel-air ratio setpoint at a second predetermined interval that is longer than the first predetermined interval. In some implementations, the enclosed combustion device may further comprise a catalyst positioned in an exhaust opening of the burner housing. In some implementations, the blower assembly further comprises an air filter positioned in the air plenum between the blower motor and the throttle valve. In some implementations, the enclosed combustion device may further comprise a fuel shutoff valve and wherein the logic of the electronic control module is further configured to detect a combustion level that may cause visible emissions from the enclosed combustion device and, upon detecting a combustion level that may cause visible emissions, the logic causes the processor to send a signal to the fuel shutoff valve activating the fuel shutoff valve. In some implementations, the logic causes the electronic control module to send a message alerting an operator of the activation of the fuel shutoff valve.

Consistent with an aspect of the present disclosure, an enclosed combustion device may comprise: a housing comprising an outer housing and a burner housing, the burner housing situated inside the outer housing and separated from the outer housing by an air gap; a temperature sensor and an exhaust gas oxygen sensor mounted to and extending inside the burner housing; a burner assembly mounted inside the burner housing for burning a fuel, the burner assembly having a burner, a fuel-air mixing nozzle connectable to a source of the fuel, an air tube connecting the burner and the fuel-air mixing nozzle, a fuel supply pressure sensor, a variable speed blower motor, a variable frequency drive (VFD) connected to the variable speed blower motor, and an air intake plenum connecting the variable speed blower motor and the fuel-air mixing nozzle; and an electronic control module having a processor and a non-transitory computer readable memory storing logic, the electronic control module in communication with the VFD, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor; wherein the logic of the electronic control module is configured to receive input signals from the VFD, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor and cause the processor to calculate an actual fuel-air ratio using the received input signals, cause the processor to compare the actual fuel-air ratio to a fuel-air ratio setpoint, and the cause the processor to send a signal to the VFD to cause the VFD to adjust a blower speed of the variable speed blower motor to control a rate and volume of air from the variable speed blower motor to the fuel-air mixing nozzle if the actual fuel-air ratio and the fuel-air ratio setpoint are different. In some implementations, the enclosed combustion device may further comprise a flame detector, a coil, and an ignitor, wherein the logic of the electronic control device is further configured to receive a first signal from the flame detector indicating that a flame is no longer present in the burner and a second signal from the flame detector indicating that the flame is present in the burner, and in response to receiving the first signal the logic causes the electronic control device to perform at least one re-ignition cycle, the re-ignition cycle may comprise: sending, by the processor of the electronic control device, a signal to the coil causing the coil to send an electrical current to the ignitor which causes the ignitor to spark; and sending, by the flame detector, one of the first signal and the second signal to the electronic control device. In some implementations, the enclosed combustion device may further comprise a fuel shutoff valve installed between the source of the fuel and the fuel-air mixing nozzle, and wherein the logic of the electronic control device is further configured to perform a predetermined number of re-ignition cycles and, if the second signal is received from the flame detector after a last one of the predetermined number of re-ignition cycles, the logic of the electronic control device causes the processor to send a signal to the fuel shutoff valve activating the fuel shutoff valve preventing fuel from reaching the fuel-air mixing nozzle.

Consistent with an aspect of the present disclosure, an enclosed combustion device may comprise: a housing comprising an outer housing and a burner housing, the burner housing situated inside the outer housing and separated from the outer housing by an air gap; a temperature sensor mounted to and extending inside the burner housing; a burner assembly mounted inside the burner housing for burning a fuel, the burner assembly having a burner mounted inside a burner chamber, an exhaust gas oxygen sensor mounted to and extending inside the burner chamber, a fuel supply line, a fuel supply pressure sensor installed in the fuel supply line, an air plenum, a fuel-air mixing nozzle, an air tube connecting the burner and the fuel-air mixing nozzle, a variable speed blower motor connected to the air plenum, a variable frequency drive (VFD) connected to the variable speed blower motor, and an ambient air intake concentrically surrounding and extending at least partially over the fuel-air mixing nozzle to draw ambient air around the fuel-air mixing nozzle and into the air tube; and an electronic control module having a processor and a non-transitory computer readable memory storing logic, the electronic control module in communication with the VFD, the temperature sensor, the exhaust gas oxygen, and the fuel supply pressure sensor; wherein the logic of the electronic control module is configured to receive input signals from the VFD, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor and cause the processor to calculate an actual fuel-air ratio using the received input signals, cause the processor to compare the actual fuel-air ratio to a fuel-air ratio setpoint, and the cause the processor to send a signal to the VFD to cause the VFD to adjust a blower speed of the variable speed blower motor to control a rate and volume of air from the variable speed blower motor to the fuel-air mixing nozzle if the actual fuel-air ratio and the fuel-air ratio setpoint are different. In some implementations, the enclosed combustion device may further comprise a pilot valve connected to the fuel supply line, wherein the pilot valve is positioned adjacent to the burner to ignite a fuel-air mixture in the burner. In some implementations, the burner assembly is a first burner assembly and the combustion device may further comprise at least one second burner assembly and a first air plenum of the first burner assembly and a second air plenum of the second burner assembly are connected to an air manifold, the air manifold connected to the variable speed blower motor to distribute air from the variable speed blower motor to both the first burner assembly and the second burner assembly.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings, which are not intended to be drawn to scale, and in which like reference numerals are intended to refer to similar elements for consistency. For purposes of clarity, not every component may be labeled in every drawing.

FIG. 1 is a diagrammatic view of an air assisted enclosed combustion device having an electronic control system.

FIG. 2 is a diagrammatic view of the air assisted enclosed combustion device in accordance with one embodiment of the present disclosure.

FIG. 3 is a diagrammatic view of an individual burner assembly of the air assisted enclosed combustion device in accordance with one embodiment of the present disclosure.

FIG. 4 is a diagrammatic view of another embodiment of an individual burner assembly of an air assisted enclosed combustion device in accordance with one embodiment of the present disclosure.

FIG. 5 is a front elevational view of another embodiment of an air assisted enclosed combustion device in accordance with one embodiment of the present disclosure.

FIG. 6 is a partial cutaway, front elevational view of the air assisted enclosed combustion device of FIG. 5.

FIG. 7 is a partial cutaway, perspective view of a blower assembly and burner assemblies of the air assisted enclosed combustion device of FIG. 5.

FIG. 8 is a partial cutaway front elevational view of portions of an air intake assembly and the burner assemblies of the air assisted enclosed combustion device of FIG. 5.

FIG. 9 is a flow chart illustrating a method of burner control in accordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Before explaining at least one embodiment of the disclosure in detail, it is to be understood that the disclosure is not limited in its application to the details of construction, experiments, exemplary data, and/or the arrangement of the components set forth in the following description or illustrated in the drawings unless otherwise noted.

The systems and methods as described in the present disclosure are capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for purposes of description, and should not be regarded as limiting.

The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements.

As used in the description herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, unless otherwise noted, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements, but may also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Further, unless expressly stated to the contrary, “or” refers to an inclusive and not to an exclusive “or”. For example, a condition A or B is satisfied by one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

In addition, use of the “a” or “an” are employed to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of the inventive concept. This description should be read to include one or more, and the singular also includes the plural unless it is obvious that it is meant otherwise. Further, use of the term “plurality” is meant to convey “more than one” unless expressly stated to the contrary.

As used herein, any reference to “one embodiment,” “an embodiment,” “some embodiments,” “one example,” “for example,” or “an example” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearance of the phrase “in some embodiments” or “one example” in various places in the specification is not necessarily all referring to the same embodiment, for example.

Circuitry, as used herein, may be analog and/or digital components, or one or more suitably programmed processors (e.g., microprocessors) and associated hardware and software, or hardwired logic. Also, “components” may perform one or more functions. The term “component” may include hardware, such as a processor (e.g., microprocessor), a combination of hardware and software, and/or the like. Software may include one or more computer executable instructions that when executed by one or more components cause the component to perform a specified function. It should be understood that the algorithms described herein may be stored on one or more non-transitory computer readable memory. Exemplary non-transitory memory may include random access memory, read only memory, flash memory, and/or the like. Such non-transitory memory may be electrically based, optically based, and/or the like.

Referring now to the drawings, and in particular to FIG. 1, shown therein is a diagrammatic view of an air assisted enclosed combustion device 10 having an electronic control system 11 for controlling the air assisted enclosed combustion device 10.

The electronic control system 11 is provided with an electronic control module 12, one or more external systems 14 connected to the electronic control module 12 via a network 16, a power supply 18, a variable frequency drive (VFD) 20 connected to a blower 22, and a suite of sensors connected to the electronic control module 12 that may include a universal exhaust gas oxygen sensor (UEGO) 24, a fuel supply pressure sensor (FSP) 26, a fuel supply temperature sensor (FST) 28, an air supply pressure sensor (ASP) 30, an air supply temperature sensor (AST) 32, a barometric pressure sensor (BPS) 34, a temperature sensor (TIC or RTD) 36, and a flame detector 38 which may be an ultra violet (UV) flame detector. Ignition coils 40 a-40 n may be connected to and controlled by the electronic control module 12 to ignite n number of burners in the air assisted enclosed combustion device 10 as described further herein. Alternatively, ignition coils 40 a-40 n may ignite pilot flames which in turn ignite the burners in the air assisted enclosed combustion device 10. It should be noted that the electronic control system 11 may be provided with other sensors not specifically mentioned herein but may perform one or more functions that will be described herein regarding control of the air assisted enclosed combustion device 10. In some embodiments, the electronic control system 11 may include one or more fuel venturi pressure sensors 42 (see FIG. 3) and a shutoff valve 44 (see FIG. 3). In other embodiments such as the ones illustrated in FIGS. 3 and 4, a blower speed sensor 46 may be included that provides a current speed of a blower motor.

The electronic control module 12 of the electronic control system 11 may include, but is not limited to implementation as a single-board computer (SBC) which refers to any complete computer built on a single circuit board and contains functional computer components including a processor 50, input/output (I/O) 52, non-transitory computer readable memory 54 storing software 56 that when executed by the processor 50 causes the electronic control system 11 to perform the functions described herein, and a communication interface 58 connecting the electronic control module 12 to the network 16.

The processor 50 of the electronic control module 12 may be implemented as a single processor or multiple processors working together or independently to perform a task. In some embodiments, the electronic control module 12 may be partially or completely network-based or cloud based. The electronic control module 12 might be in a single physical location.

In some embodiments, the electronic control system 11 may be distributed, and the electronic control module 12 may communicate with the one or more external systems 14 via the network 16. As used herein, the terms “network-based,” “cloud-based,” and any variations thereof, are intended to include the provision of configurable computational resources on demand via interfacing with a computer and/or computer network, with software and/or data at least partially located on a computer and/or computer network.

In some embodiments, the network 16 may be the internet and/or other network. For example, if the network 16 is the internet, a primary user interface of the electronic control system 11 may be delivered through a series of web pages or private internal web pages of a company or corporation, which may be written in hypertext markup language. It should be noted that the primary user interface of the electronic control system 11 may be another type of interface including, but not limited to, a Windows-based application, a tablet-based application, a mobile web interface, and/or the like.

The network 16 may be almost any type of network. For example, in some embodiments, the network 16 may be a version of an internet network (e.g., exist in a TCP/IP-based network). It is conceivable that soon, embodiments within the present disclosure may use more advanced networking technologies.

In some embodiments, the external system 14 may optionally communicate with the electronic control module 12. For example, in one embodiment of the electronic control system 11, the external system 14 may supply data transmissions via the network 16 to the electronic control module 12 regarding real-time or substantially real-time events (e.g., user updates, real-time software updates, and/or software updates to be installed later). Data transmission may be through any type of communication including, but not limited to, speech, visuals, signals, textual, and/or the like. Events may include, for example, data transmissions regarding user messages or updates from an administrator, for example, initiated via the external system 14. It should be noted that the external system 14 may be the same type and construction as the electronic control module 12.

An interface device 60 may be connected to the electronic control module 12 to allow input from a user and for graphical display of information such as a status of the electronic control system 11. The interface device 60 may be connected to the input/output (I/O) 52 of the electronic control module 12 and may be implemented as a single device, such as, for example, a touchscreen. It should be noted that interface device 60 may be implemented as the separate input and output devices. For instance, a separate input device may include, but is not limited to, implementation as a keyboard, touchscreen, mouse, trackball, microphone, fingerprint reader, infrared port, slide-out keyboard, flip-out keyboard, cell phone, PDA, remote control, fax machine, wearable communication device, network interface, an NFC enabled card, combinations thereof, and/or the like and a separate output device may include, but is not limited to, a computer monitor, a screen, a touchscreen, a speaker, a website, a television set, a smart phone, a PDA, a cell phone, a laptop computer, combinations thereof, and the like, for example. While the interface device 60 is illustrated connected to the input/output 52, it should be noted that in some embodiments, the electronic control module 12 may include a connection adapted specifically to connect devices such as interface device 60.

The electronic control module 12 may be enclosed in a control box 70 that houses and protects the electronic control module 12 and the interface device 60. An on/off switch 72 may be provided that controls power to the electronic control module 12. An emergency stop button 74 may be provided to cut power to the electronic control system 11 if an emergency occurs. One or more fuel lockoffs 76 may be included.

Referring now to FIG. 2, the air assisted enclosed combustion device (AAECD) 10 is illustrated having an outer housing 102 separated by an air gap 104 from a burner housing 106. The AAECD 10 is provided with burners 108 a-108 n connected to an air manifold 110 via air tubes 112 a-112 n. An air plenum 114 having an air throttle valve 116 connects a blower 118 to the air manifold 110. A throttle valve controller 117 may be connected to the throttle valve 116 to rotate or move the throttle valve 116 to a desired position. A filter 120 may be inserted into the air plenum 114 to filter air from the blower 118 before it enters the air manifold 110. The air plenum 114, air throttle valve 116, throttle valve controller 117, blower 118, and filter 120 form a blower assembly 121.

Fuel is supplied to the AAECD 10 from a source of fuel (not shown) through a supply line 130 connected to a fuel manifold 132. Fuel nozzles (not shown) inject fuel into the air manifold 110 and the fuel and air are drawn into and mix in the air tubes 112 a-112 n before igniting at the burners 108 a-108 n. A catalyst 140 positioned at an exhaust opening 142 of the burner housing 106 catalyzes unburned or partially burned fuel constituents to ensure that no volatile organic compounds are discharged from the exhaust stack.

AAECD 10 is provided with the electronic control module 12 connected to the temperature sensor 36, the exhaust gas oxygen sensor 24, the flame detector 38, the fuel supply pressure sensor 26, and the throttle valve controller 117. The electronic control module 12 receives inputs from the sensors 24, 26, 36, and 38 and the throttle valve controller 117 and processes these inputs along with other calibration parameters using software 56 programmed with algorithms described further herein and outputs a desired mass air flow translated to a position for air throttle valve 116 sent to the throttle valve controller 117 which rotates or otherwise positions the throttle valve 116. The position of air throttle valve 116 controls a rate and volume at which air from the blower 118 enters the air manifold 110 and consequently the air/fuel mixture that reaches the burners 108 a-108 n. For instance, when a leaner air/fuel mixture is desired, the electronic control module 12 may send a signal to the throttle valve controller 117 which causes the throttle valve controller 117 to open the air throttle valve 116 more to allow more air to pass through resulting in relatively more air to fuel in the air/fuel mixture. When a richer air/fuel mixture is desired, the electronic control module 12 may send a signal to the throttle valve controller 117 which causes the throttle valve controller 117 to close the air throttle valve 116 more to allow less air to pass through resulting in relatively more fuel to air in the air/fuel mixture.

During operation of the AAECD 10, the electronic control module 12 operates automatically, meaning without human intervention, adjusting the air/fuel mixture as necessary to maintain efficient combustion of fuel. The AAECD 10 may be provided with systems necessary to automatically shut down the AAECD 10 should the electronic control module 12 detect a combustion level that may cause visible emissions from the AAECD 10 and/or that a flame in one or more of the burners 108 a-108 n has gone out. For instance, the electronic control module 12 may activate a fuel shutoff valve (not shown) and cut power to the AAECD 10 to stop combustion at the burners 108 a-n. The software 56 of the electronic control module 12 may then be programmed to cause the electronic control module 12 to send a message to a human operator alerting them to the shutdown. By way of non-limiting example, the message may be in the form of an SMS text message, an email, an automated phone call, or an audible alarm.

Referring now to FIG. 3, a burner assembly 200 constructed in accordance with one embodiment of the present disclosure is illustrated. The burner assembly 200 is illustrated connected to and controlled by an electronic control system similar in makeup and function to the electronic control system 11 of FIG. 1. Therefore, in the interest of brevity, like elements will be numbered the same and only the differences will be described in detail.

The burner assembly 200 is provided with a burner 202, at least one ignitor 203 connected to coil 40 a, an air tube 204, a fuel-air mixing nozzle 206, an air intake plenum 208 connected to a variable-speed blower 210. Burner assembly 200 is further illustrated having a fuel supply 220 connected to the burner assembly 200 via fuel supply line 222. Fuel supply line 222 is provided with a manual shutoff valve 224 and an electronic shutoff valve 44 controlled by the electronic control module 12. In one embodiment of the disclosure a pressure regulator 226 is used to further condition the fuel feeding the fuel-air mixing nozzle 206 to achieve a desired fuel-air ratio by tracking fuel pressure relative to air pressure by use of a pressure balance line 227 connected to air intake plenum 208.

The electronic control module 12 receives inputs from the sensors (e.g., 24, 26, 30, 36, 38, and 42) and processes these inputs along with other calibration parameters in the software 56 with algorithms described further herein and outputs a desired mass air flow translated to a variable frequency drive speed control signal and sent to the VFD 20. The VFD 20 then converts the control signal to the necessary frequency and voltage to control a blower speed of the variable speed blower 210. The blower speed of the variable speed blower 210 controls a rate and volume at which air from the variable speed blower 210 enters the air plenum 208 and consequently the air/fuel mixture that reaches the burner 202.

The flame detector 38 may be configured to send a first signal to the electronic control module 12 indicating there is no flame in the burner 202 and a second signal to the electronic control module indicating that a flame is present in the burner 202. When the flame detector 38 sends the first signal, the electronic control module 12 may be programmed to send a signal to the coil 40 a that causes the coil 40 a to send an electrical current to the at least one ignitor 203 that causes the at least one ignitor to spark in order to re-ignite the burner 202. The electronic control module 12 may be programmed to then receive one of the first signal and the second signal from the flame detector 38 indicating the presence or absence of a flame. If the first signal is received indicating that the flame has not been re-ignited in the burner 202, the electronic control module 12 may be programmed to attempt this re-ignition cycle a predetermined number of times before activating the electronic shutoff valve 44 if a flame is not detected in the burner 202. If the second signal is received by the electronic control module 12, the re-ignition cycle is ended and the electronic control module 12 resumes a closed-loop operation of the burner assembly 200 as described in more detail herein.

Referring now to FIG. 4, illustrated is a burner assembly 300 in accordance with another embodiment of the presently disclosed inventive concepts. The burner assembly 300 is illustrated connected to and controlled by an electronic control system similar in makeup and function to the electronic control system 11 of FIG. 1. Therefore, in the interest of brevity, like elements will be numbered the same and only the differences will be described in detail.

The burner assembly 300 is provided with a burner chamber 302, a burner 304, an air tube 306, a fuel-air mixing nozzle 308, an ambient air inlet 310, an air plenum 312, a variable speed blower 314, a fuel supply line 320, a fuel shutoff valve 322, a back-flow check valve 324, a pilot valve 330, a pilot valve shutoff 332, a pilot flame temperature sensor 334, an ignitor 340, and a universal exhaust gas oxygen (UEGO) sensor 350 which samples air from burner chamber 302 thru sampling tube 354 and vents back to air tube 306 thru return tube 352.

The electronic control module 12 receives inputs from the sensors (e.g., 24, 26, 28, 30, 32, 34, 36, 38, 42, 46 and 334) and processes these inputs along with other calibration parameters in the software 56 with algorithms described further herein and outputs a desired mass air flow translated to a variable frequency drive speed control signal and sent to the VFD 20. The VFD 20 then converts the variable frequency drive speed control signal to the necessary frequency and voltage to control a blower speed of the variable speed blower 314. The blower speed of the variable speed blower 314 controls a rate and volume at which air from the variable speed blower 314 enters the air plenum 312 and consequently the air/fuel mixture that reaches the burner 304 to be ignited by the ignitor 340 and/or the pilot flame 330.

In operation of the burner assembly 300, air is drawn in through the variable speed blower 314 and directed to the fuel-air mixing nozzle 308. Additional ambient air is drawn in through the ambient air inlet 310 at one pressure (typically at or about ambient air pressure) and mixes with a fuel-air mixture from the fuel-air nozzle 308 which has a different pressure and velocity because of the variable speed blower motor 314. This causes the ambient air to be drawn into the fuel-air mixture and further mixed in the air tube 306 which leads to greater mixing of the fuel and air and a more efficient burn at the burner 304.

The oxygen sensor 350 senses the fuel-air ratio in the burned fuel-air mixture in burner chamber 302 by drawing a gas sample through sampling tube 354 to the oxygen sensor 350 then returning it through return tube 352 back to the fuel-air mixture in air tube 306. The oxygen sensor 350 sends a signal to the electronic control module 12 indicative of fuel-air ratio data. The electronic control module 12 uses the fuel-air ratio data to determine an actual fuel-air ratio which relates to the efficiency of the burner assembly 300 and adjust the fuel-air mixture as necessary to achieve an efficient and clean burn.

The burner chamber 302 allows precise control of the combustion process in a controlled environment. Because of the cup-shape of the burner chamber that surrounds the burner 304, draft air that normally passes through a housing of an AAECD such as AAECD 300 will not interfere with the precise fuel-air mixture that enters the burner chamber 302 for combustion.

Referring now to FIGS. 5-8, an air assisted enclosed combustion device (AAECD) 400 is illustrated. The AAECD 400 is provided with a housing 402, usually circular in design or at least geometric in such a way that it makes a 360-degree enclosure that has at least one intake 404 for air to enter and an exhaust 406 for exhaust (combustion byproducts) to escape.

The housing 402 may be constructed having an upper portion 408 and a lower portion 410, the upper portion 408 adapted to be affixed to the lower portion 410. The upper portion 408 and the lower portion 410 may be affixed together using methods known and understood in the art. For instance, in the illustrated embodiment the upper portion 408 is provided with a flange 412 and the lower portion 410 is provided with a flange 414 that mates with flange 412 of the upper portion 408. The flanges 412 and 414 may be provided with apertures (not shown) sized and aligned to accept bolts (not shown) to affix the upper portion 408 to the lower portion 410.

To provide access for service, the AAECD 400 may be provided with a service access door 420 shown in FIG. 5 situated in the lower portion 410.

The AAECD 400 may be provided with a heat skirt 416 surrounding at least a portion of the upper portion 408 of the housing 402. The heat skirt 416 is sized and positioned to form an air gap 418 between an inner surface 417 of the heat skirt 416 and an outer wall 419 of the upper portion 408 of the housing 402.

In some embodiments, the AAECD 400 may be provided with flame arrestors 424 (only one of which is numbered) installed so if combustible gas is drawn into the at least one intake 404 from outside the housing 402, a flame within the housing 402 will not propagate through the intake 404 to outside the housing 402 and cause a fire or explosion external to the AAECD 400.

Fuel enters the housing 402 through an aperture 428 extending through the lower portion 410, the aperture 428 sized and shaped so a fuel line 430 may pass through. Fuel is directed from a fuel supply (not shown) through the fuel line 430 and into a fuel manifold 432, which directs fuel to a fuel nozzle 434 (only one of which is numbered) adapted to inject fuel in a manner that promotes good mixing of fuel with the air.

In some embodiments (not shown) the AAECD 400 may be provided with a fuel shut off valve (not shown) in the fuel line 430 which may be positioned inside or outside the housing 402 to control the flow of fuel into the AAECD 400 with electronic control module 12.

A variable speed blower 440 is located inside the lower portion 410 of the housing 402 to draw air in, compress the air, and exhaust it. This compressed air is routed through a plenum 444 which directs the compressed air into manifolds 446 (only one of which is numbered) to an air inlet side 448 of a fuel-air mixing nozzle 450. Fuel is injected into the fuel-air mixing nozzle 450 by the fuel nozzle 434. Both fuel and air enter the fuel-air mixing nozzle 450 under pressure mixing the fuel and air together. The design of the fuel-air mixing nozzle 450 aids in the mixing process. An exemplary fuel-air mixing nozzle is illustrated in more detail in FIG. 4.

The fuel-air mixture exits the fuel-air mixing nozzle 450 and is propelled through a mixing chamber 460 that further promotes fuel-air mixing by providing turbulence and time before the fuel-air mixture reaches burner chamber(s) 480. In some embodiments, the mixing chamber 460 may be designed and operate similar to the air tube 306 illustrated in FIG. 4. In particular, the mixing chamber 460 may be provided with an ambient air inlet (not shown) that promotes turbulence in the mixing chamber 460.

The fuel-air mixture enters the burner chamber 480 through a flame arrestor 482. The flame arrestor 482 prevents flashback into the mixing chamber 460 and fuel-air mixing nozzle 450. Upon entering the burner chamber 480 the mixture is ignited by an ignitor 491, which may be a pilot flame present in each burner chamber 480. Ignition occurs and a flame burns in the burner chamber 480 at the desired fuel-air ratio producing clean and complete combustion. No additional air is required for complete combustion. An optimized ratio of fuel to air depends on the composition of the fuel being used and the desired combustion chemistry, but a desired ratio of fuel to air is in a range between 0.05:1 to 0.10:1 fuel-to-air ratio by mass.

The flame is contained within a cup shaped inner portion 484 of the burner chamber 480 at low flow rates and extends over a top 486 of the burner chamber 480 at high flow rates. The rising heat from the flame in the burner chamber 480 promotes a draft of air from the intake 404 and up and around the burner chamber 480. This draft air flow cools any flame that extends over the top 486 of the burner chamber 480 to prevent excess heat on an inner wall 490 of the housing 402. Exhaust from combustion exits out the exhaust 406 formed in the housing 402 into the atmosphere.

The heat skirt 416 further comprises a first end 492, a second end 494, and a width 496 extending from the first end 492 to the second end 494. The heat skirt 416 comprises a material, such as steel, for instance, that withstands heat and is strong enough to prevent objects from coming into contact with covered portions of the outer wall 419 of the housing 402. The heat skirt 416 is sized and positioned to prevent injury and/or visual evidence of fire that exists inside the inner wall 490 of the housing 402. The first end 492 of the heat skirt 416 is positioned at a level just below the top 486 of the burner chamber 480. The width 496 of the heat skirt 416 is determined by a height of a possible flame that could extend over the top 486 of the burner chamber 480 plus a predetermined width for added safety so excess heat will not excessively heat a portion of the inner 490 or outer wall 419 of the housing 402 that extends above the second end 494 of the heat skirt 416. In other words, when the AAECD 400 is used to burn highly combustible material or material at a high pressure so the flame may extend farther over the top 486 of the burner chamber 480, the width 496 of the heat skirt 416 would be greater. The air gap 418 between the outer wall 419 and the inner surface 417 of the heat skirt 416 acts to insulate and dissipate the excess heat. The heat skirt 416 also prevents visible signs of combustion heat from outside the AAECD 400 without the use of high maintenance and costly items like thermal insulation or wraps

Referring now to FIG. 9, a flow chart of a burner control strategy is illustrated. For illustration, and not by way of limitation, the burner control strategy will be described using the electronic control system 11 deployed in AAECD 400. However, the burner control strategy may be used with any electronic control system equipped with the described hardware and software and deployed in a properly equipped AAECD.

In step 500, the electronic control module 12 receives data from the fuel supply pressure sensor 26, fuel supply temperature sensor 28, and barometric pressure sensor 34. Using this data, along with the physical flow characteristics of the fuel-air mixing nozzle 450 (i.e., orifice fuel flow area, discharge coefficient, and gas composition properties in step 502), the electronic control module 12 calculates a mass flow rate of fuel thru the fuel-air mixing nozzle 450.

In step 504, the electronic control system 11 provides a desired fuel equivalence ratio (PHI) value and air ratio as a function of mass fuel flow rate thru each fuel-air mixing nozzle 450. Fuel PHI is the ratio of (actual fuel-air ratio)/(stoichiometric fuel-air ratio). An exemplary formula is found in 504 a.

With the mass fuel flow rate and PHI determined, the desired mass air flow rate from the variable speed blower 440 can be determined in step 506. An exemplary formula for calculating mass air flow rate is found in 506 a.

In step 508, the electronic control module 12 receives data from the barometric pressure sensor 34 and the air supply temperature sensor 32 and uses the data to calculate air density and an actual volume air flow rate desired from the variable speed blower 440.

In step 510, the electronic control module 12 uses the actual volume air flow rate desired from the variable speed blower 440 calculated in step 508, along with the physical flow characteristics of the fuel-air mixing nozzle 450 and a rated supply pressure of the variable speed blower 440 (i.e., orifice air flow area, discharge coefficient, and air properties), to determine a desired blower speed that will produce the actual volume air flow rate desired.

In step 512, the electronic control module 12 calculates and sends a control signal to the VFD 20.

In step 514, the VFD 20 converts the control signal to a necessary frequency and voltage to drive the variable speed blower 440 to the desired speed and outputs the necessary frequency and voltage to drive the variable speed blower 440 which spins up to the desired speed (RPM).

In step 516, the electronic control module 12 calculates an air supply pressure and air supply temperature multiplier (ASP_AST_mult) using the formula in box 516 a to correct for non-standard ambient conditions.

In step 518, the electronic control module 12 calculates an expected air supply pressure (ASP_exp) using the formula in box 518 a. The electronic control module 12 then calculates a final expected air supply pressure (ASP_exp_Final) using the formula in box 518 a.

The above procedure is accurate if the variables that are entered into the control calculations are all known and accurate. In the real world, some of these variables are not constant and are not always known accurately. The factors that affect the accuracy of these control calculations include:

-   -   Fuel gas composition     -   Local weather (i.e., barometric pressure and air temperature)     -   Production part-to-part variability of the nozzle, blower, VFD.     -   Repeatability, accuracy, and temperature drift of the sensors

To account for the variations that cause inaccuracies in the control calculations, the electronic control system 11 uses the UEGO sensor 24 positioned in or above the burner chamber 480 for direct measurement of combustion performance. The UEGO sensor 24 measures a resulting fuel-air equivalence ratio of combustion that includes the effects of all the changing variables mentioned above. The UEGO sensor 24 provides a feedback signal that allows closed-loop control of the air flow rate for optimum combustion.

In step 520, using input from the sensors, the electronic control system 11 enters closed-loop proportional-integral-derivative (PID) operation to automatically maintain the desired combustion quality. The electronic control system 11 maintains a first-closed loop on the variable speed blower 440 RPM and a second closed-loop on a PHI (fuel-air equivalence ratio) setpoint. The first closed-loop is a “quick loop” since a change in variable speed blower 440 speed to the speed control command from the electronic control module 12 can be sensed almost immediately. This makes sure that any error in PHI is not caused by an error in air flow caused by a change in variable speed blower 440 speed. The second-closed loop is a “slow loop” and is for PHI, or fuel-air ratio, control. The second closed-loop compares the actual fuel-air ratio (feedback) from the UEGO sensor 24 to the fuel-air ratio setpoint in the calibration in the electronic control module 12. If these two values are not equal, the electronic control module 12 adjusts the variable speed blower 440 RPM setpoint to either lean or richen the mixture dependent on the direction of the error in PHI. If the mixture is lean, then the variable speed blower 440 RPM is reduced to richen the mixture. If the mixture is rich, then the variable speed blower 440 RPM is increased to lean the mixture. The amount of the correction depends on the error value. Those skilled in the art of PID closed-loop control can easily determine how this closed-loop function works to correct PHI. The second closed-loop is considered slow because there is latency between the time when the set point command to the variable speed blower 440 is changed to correct PHI and the time the UEGO 24 senses the change in actual fuel-air ratio. This latency can be from a few seconds to approximately 30 seconds.

It should be noted that while step 520 has been described in operation using the electronic control system 11 deployed in AAECD 400, a similar process may be used with AAECD 10 operating blower motor 118 where the air-fuel mixture is controlled by adjusting throttle valve 116. In such an embodiment, the first closed-loop may be the electronic control module 12 receiving a signal from the throttle valve controller 117 indicating a position of the throttle valve 116 where a change in the position of the throttle valve 116 would indicate a change in the air-flow. The second closed-loop would operate the same way described above with the exception that if the actual fuel-air ratio and the fuel-air ratio setpoint were different, the electronic control module 12 would send a signal to the throttle valve controller 117 that would cause the throttle valve controller 117 to the adjust the position of the throttle valve 116 to adjust the fuel-air ratio. For instance, to lean out the fuel-air ratio, the electronic control module 12 would send a signal to the throttle valve controller 117 causing the throttle valve controller 117 to open the throttle valve 116 a desired amount allowing more air from the blower to reach the burners 108 a-108 n. To richen the air-fuel mixture, the electronic control module 12 would send a signal to the throttle valve controller 117 causing the throttle valve controller 117 to close the throttle valve 116 a desired amount allowing less air from the blower to reach the burners 108 a-108 n.

In step 524, the electronic control system 11 performs a fault check to determine if the control loop is functioning properly. The electronic control system 11 compares a current RPM of the variable speed blower 440, the air supply pressure, and an expected air supply pressure to determine an air supply pressure error. If the air supply pressure error is greater than +/−10% from an air supply pressure setpoint at the current RPM of the variable speed blower 440, the electronic control system 11 sets a fault and attempts to determine a cause and solution by first iterating through steps 500-518. If the cause cannot be determined or solved by iterating through steps 500-518, the electronic control system 11 may alert a human operator by sending a message, for instance, to the one or more external systems 14 over the network 16 indicating manual intervention is required.

From the above description, it is clear that the inventive concepts disclosed herein are well adapted to carry out the objects and to attain the advantages mentioned herein as well as those inherent in the inventive concepts disclosed herein. While presently preferred embodiments of the inventive concepts disclosed herein have been described for purposes of this disclosure, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the scope and coverage of the inventive concepts disclosed herein. 

What is claimed is:
 1. An enclosed combustion device, comprising: a housing comprising an outer housing and a burner housing, the burner housing situated inside the outer housing and separated from the outer housing by an air gap; a temperature sensor and an exhaust gas oxygen sensor mounted to the burner housing; a burner assembly mounted inside the burner housing for burning a fuel, the burner assembly having at least one burner connected to an air manifold and a fuel manifold, the fuel manifold having a fuel supply pressure sensor and connectable to a source of the fuel; a blower assembly connected to the air manifold, the blower assembly having a blower motor, an air plenum, and a throttle valve controller operably connected to a throttle valve situated inside the air plenum; and an electronic control module having a processor and a non-transitory computer readable memory storing logic, the electronic control module in communication with the throttle valve controller, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor; wherein the logic of the electronic control module is configured to receive input signals from the throttle valve controller, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor and cause the processor to calculate an actual fuel-air ratio using the received input signals, the logic further configured to cause the processor to compare the actual fuel-air ratio to a fuel-air ratio setpoint and cause the processor to send a signal to the throttle valve controller to cause the throttle valve controller to move the throttle valve to a desired position to control a rate and volume of air from the blower motor to the at least one burner if the actual fuel-air ratio and the fuel-air ratio setpoint are different.
 2. The enclosed combustion device of claim 1, wherein the electronic control module is configured to operate the enclosed combustion device in a closed-loop by calculating the actual fuel-air ratio and comparing the actual fuel-air ratio to a fuel-air ratio setpoint at predetermined intervals.
 3. The enclosed combustion device of claim 2, wherein the closed-loop is further defined as a first-closed loop that determines a position of the throttle valve at a first predetermined interval and a second closed-loop that determines the actual fuel-air ratio and compares the actual fuel-air ratio to the fuel-air ratio setpoint at a second predetermined interval that is longer than the first predetermined interval.
 4. The enclosed combustion device of claim 1, further comprising a catalyst positioned in an exhaust opening of the burner housing.
 5. The enclosed combustion device of claim 1, wherein the blower assembly further comprises an air filter positioned in the air plenum between the blower motor and the throttle valve.
 6. The enclosed combustion device of claim 1, further comprising a fuel shutoff valve and wherein the logic of the electronic control module is further configured to detect a combustion level that may cause visible emissions from the enclosed combustion device and, upon detecting a combustion level that may cause visible emissions, the logic causes the processor to send a signal to the fuel shutoff valve activating the fuel shutoff valve.
 7. The enclosed combustion device of claim 6, wherein the logic causes the electronic control module to send a message alerting an operator of the activation of the fuel shutoff valve.
 8. An enclosed combustion device, comprising: a housing comprising an outer housing and a burner housing, the burner housing situated inside the outer housing and separated from the outer housing by an air gap; a temperature sensor and an exhaust gas oxygen sensor mounted to and extending inside the burner housing; a burner assembly mounted inside the burner housing for burning a fuel, the burner assembly having a burner, a fuel-air mixing nozzle connectable to a source of the fuel, an air tube connecting the burner and the fuel-air mixing nozzle, a fuel supply pressure sensor, a variable speed blower motor, a variable frequency drive (VFD) connected to the variable speed blower motor, and an air intake plenum connecting the variable speed blower motor and the fuel-air mixing nozzle; and an electronic control module having a processor and a non-transitory computer readable memory storing logic, the electronic control module in communication with the VFD, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor; wherein the logic of the electronic control module is configured to receive input signals from the VFD, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor and cause the processor to calculate an actual fuel-air ratio using the received input signals, cause the processor to compare the actual fuel-air ratio to a fuel-air ratio setpoint, and cause the processor to send a signal to the VFD to cause the VFD to adjust a blower speed of the variable speed blower motor to control a rate and volume of air from the variable speed blower motor to the fuel-air mixing nozzle if the actual fuel-air ratio and the fuel-air ratio setpoint are different.
 9. The enclosed combustion device of claim 8, wherein the electronic control module is configured to operate the enclosed combustion device in a closed-loop by calculating the actual fuel-air ratio and comparing the actual fuel-air ratio to a fuel-air ratio setpoint at predetermined intervals.
 10. The enclosed combustion device of claim 9, wherein the closed-loop is further defined as a first-closed loop that determines the blower speed of the variable speed blower motor at a first predetermined interval and a second closed-loop that determines the actual fuel-air ratio and compares the actual fuel-air ratio to the fuel-air ratio setpoint at a second predetermined interval longer than the first predetermined interval.
 11. The enclosed combustion device of claim 8, further comprising a catalyst positioned in an exhaust opening of the burner housing.
 12. The enclosed combustion device of claim 8, further comprising a fuel shutoff valve installed in between the source of the fuel and the fuel-air mixing nozzle, and wherein the logic of the electronic control module is further configured to detect a combustion level that may cause emissions visible from outside the enclosed combustion device and, upon detecting a combustion level that may cause emissions visible from outside the enclosed combustion device, the logic causes the processor to send a signal to the fuel shutoff valve activating the fuel shutoff valve preventing fuel from reaching the fuel-air mixing nozzle.
 13. The enclosed combustion device of claim 12, wherein the logic causes the electronic control module to send a message alerting an operator of the activation of the fuel shutoff valve.
 14. The enclosed combustion device of claim 8, further comprising a flame detector, a coil, and an ignitor, wherein the logic of the electronic control device is further configured to receive a first signal from the flame detector indicating that a flame is no longer present in the burner and a second signal from the flame detector indicating that the flame is present in the burner, and in response to receiving the first signal the logic causes the electronic control device to perform at least one re-ignition cycle, the re-ignition cycle comprising: sending, by the processor of the electronic control device, a signal to the coil causing the coil to send an electrical current to the ignitor which causes the ignitor to spark; and sending, by the flame detector, one of the first signal and the second signal to the electronic control device.
 15. The enclosed combustion device of claim 14, further comprising a fuel shutoff valve installed between the source of the fuel and the fuel-air mixing nozzle, and wherein the logic of the electronic control device is further configured to perform a predetermined number of re-ignition cycles and, if the second signal is received from the flame detector after a last one of the predetermined number of re-ignition cycles, the logic of the electronic control device causes the processor to send a signal to the fuel shutoff valve activating the fuel shutoff valve preventing fuel from reaching the fuel-air mixing nozzle.
 16. An enclosed combustion device, comprising: a housing comprising an outer housing and a burner housing, the burner housing situated inside the outer housing and separated from the outer housing by an air gap; a temperature sensor mounted to and extending inside the burner housing; a burner assembly mounted inside the burner housing for burning a fuel, the burner assembly having a burner mounted inside a burner chamber, an exhaust gas oxygen sensor mounted to and extending inside the burner chamber, a fuel supply line, a fuel supply pressure sensor installed in the fuel supply line, an air plenum, a fuel-air mixing nozzle, an air tube connecting the burner and the fuel-air mixing nozzle, a variable speed blower motor connected to the air plenum, a variable frequency drive (VFD) connected to the variable speed blower motor, and an ambient air intake concentrically surrounding and extending at least partially over the fuel-air mixing nozzle to draw ambient air around the fuel-air mixing nozzle and into the air tube; and an electronic control module having a processor and a non-transitory computer readable memory storing logic, the electronic control module in communication with the VFD, the temperature sensor, the exhaust gas oxygen, and the fuel supply pressure sensor; wherein the logic of the electronic control module is configured to receive input signals from the VFD, the temperature sensor, the exhaust gas oxygen sensor, and the fuel supply pressure sensor and cause the processor to calculate an actual fuel-air ratio using the received input signals, cause the processor to compare the actual fuel-air ratio to a fuel-air ratio setpoint, and cause the processor to send a signal to the VFD to cause the VFD to adjust a blower speed of the variable speed blower motor to control a rate and volume of air from the variable speed blower motor to the fuel-air mixing nozzle if the actual fuel-air ratio and the fuel-air ratio setpoint are different.
 17. The enclosed combustion device of claim 16, further comprising a pilot valve connected to the fuel supply line, wherein the pilot valve is positioned adjacent to the burner to ignite a fuel-air mixture in the burner.
 18. The enclosed combustion device of claim 16, wherein the burner assembly is a first burner assembly, the combustion device further comprising at least one second burner assembly and a first air plenum of the first burner assembly and a second air plenum of the second burner assembly are connected to an air manifold, the air manifold connected to the variable speed blower motor to distribute air from the variable speed blower motor to both the first burner assembly and the second burner assembly.
 19. The enclosed combustion device of claim 16, further comprising a flame detector, a coil, and an ignitor, wherein the logic of the electronic control device is further configured to receive a first signal from the flame detector indicating that a flame is no longer present in the burner and a second signal from the flame detector indicating that the flame is present in the burner, and in response to receiving the first signal the logic causes the electronic control device to perform at least one re-ignition cycle, the re-ignition cycle comprising: sending, by the processor of the electronic control device, a signal to the coil causing the coil to send an electrical current to the ignitor which causes the ignitor to spark; and sending, by the flame detector, one of the first signal and the second signal to the electronic control device.
 20. The enclosed combustion device of claim 19, further comprising a fuel shutoff valve installed in the fuel supply line before the fuel-air mixing nozzle, and wherein the logic of the electronic control device is further configured to perform a predetermined number of re-ignition cycles if the second signal is received from the flame detector and, if the second signal is received from the flame detector after a last one of the predetermined number of re-ignition cycles, the logic of the electronic control device causes the processor to send a signal to the fuel shutoff valve activating the fuel shutoff valve preventing fuel from reaching the fuel-air mixing nozzle. 